The present invention relates generally to performing mechanical actions such as drawing or printing, and more particularly to a system for performing the mechanical actions such as drawing on and erasing whiteboards and other substantially vertical surfaces.
A great deal of work has been devoted to integrating large drawing and display surfaces with electronic document faculties. Technology has been developed to support two directions of information flow, image capture, and image display.
Image capture technologies enable marks drawn on a surface to be captured in electronic form. These include the pressure-sensitive tablets such as the SMART Board from SMART Technologies, Inc. of Calgary, Alberta, Canada, location-sensitive surfaces accompanied by special pens such as the Liveboard from Xerox Corporation of Stamford, Conn., and Mimeo from Virtual Ink Corporation of Boston, Mass., Laser-based pen trackers such as the SoftBoard from Microfield Graphics, Inc. of Portland, Oreg., camera-based scanning such as the ZombieBoard from Xerox Corporation, and 1-dimensional scan bars such as the Copyboard from Xerox Corporation. The ZombieBoard is further described in U.S. Pat. No. 5,528,290 to Saund, entitled DEVICE FOR TRANSCRIBING IMAGES ON A BOARD USING A CAMERA BASED BOARD SCANNER.
Image display technologies permit stored electronic images to be displayed on a large surface. These include plasma, active matrix, liquid crystal, light-emitting diode, and projectors which can be either front-projection or rear-projection. Of the various image display technologies, only the projectors are compatible with an inexpensive, passive, surface of variable and extensible size. All of the others require dedicated display hardware which is expensive and fixed in size.
In addition to the applications for generating images on large vertical surfaces, a variety of other applications exist such as window washing, moving physical tokens, and the like.
The present invention is a system for performing mechanical actions such as drawing on substantially vertical surfaces such as whiteboards. For convenience, the present invention is referred to as a Pendulum Whiteboard Printer. The term xe2x80x9cpendulumxe2x80x9d is chosen because the carriage for holding the effector that performs the mechanical action, called an effector platform, is suspended against the force of gravity by suspension wires. It is not a true pendulum in the x-y plane because two wires are used. While the present invention is referred to as a printer, no printing in the traditional meaning of the word is done. Rather, all marks are drawn by moving a marking element across the surface with an effector platform.
The present invention provides an inexpensive mechanism for remotely generating images on whiteboards and other substantially vertical surfaces. The term xe2x80x9cimagexe2x80x9d as used in this specification refers to any marking created by a marking element such as a dry-erase pen. The markings may be in the form of textual characters, straight or curved strokes, or any other types of marks that could be hand-drawn.
An effector platform is provided for holding an end effector such as the marking element. The effector platform is suspended by two wires from two spools placed near the upper, outer, boundaries of the surface to be marked on. The lengths of the two wires are adjusted to control the location of the effector platform over the surface to be marked on. These wires are typically wound on motorized spools permitting their lengths to be varied under computer control. The spools may be located above and beyond the ends of the target surface so that all parts of the surface are reachable. If needed, control signals to the effector platform can be provided through the wires using techniques well-known in the art. Power may be supplied to the effector platform through the wires or from an on-board battery.
In an alternative embodiment of the invention, a portable Pendulum Whiteboard Printer is provided in which the spools are either affixed to a wall or other suitable surface, or mounted on adjustable stands at appropriate locations with respect to the whiteboard. With the portable setup, a calibration routine should be run so that the system knows the drawing area of and locations on the whiteboard. However, even with a fixed embodiment of the whiteboard printer, occasional calibrations may be desirable. Such calibrations may be performed using any techniques known in the art. For example, one such calibration technique would be to move the effector platform to a known board location using feedback information such as video camera and resetting the coordinates describing the effector platform position.